Cameron Fuller, a well know Ops Mgr MVP, wrote a really good post about What does the Root Management Server Emulator actually do.
His summary :
The RMS Emulator only provides backward compatibility to management pack using things which target the ‘Root Management Server’ class instance (Target=”SC!Microsoft.SystemCenter.RootManagementServer). The RMS emulator is hosted on a management server and as such it does a lot of activities that aren’t specific to the RMSE role. Everything else the RMS used to be responsible for is managed by the “All Management Servers Resource Pool”, the “Notifications Resource Pool” and the “AD Assignment Resource Pool”.
I really invite you to read the complete story available : HERE